1. Field of the Invention
The present invention relates to a light reflecting plate, a method of manufacturing the same, and a light reflecting device using a light reflecting plate, more particularly to a light reflecting plate with excellent light reflection characteristics, a method of manufacturing the same, and a light reflecting device such as a mirror duct in which a light reflecting plate is provided on the inner wall of a light guiding section and which introduces sunlight to indoor by the light reflecting plate to illuminate the indoor, an illumination fixture equipped with a light reflecting plate of a light source, a liquid crystal display device equipped with a light reflecting plate of external incident light, an edge-lighting type backlight of a liquid crystal display device equipped with the light reflecting plate, or a liquid crystal display device equipped with the edge-lighting type backlight.
2. Description of the Related Art
Conventionally, as a light reflecting plate of a light reflecting device, a glass substrate on which aluminum (Al) film is deposited by vacuum evaporation (refer to Japanese Patent Laid-open No. 2001-235798) or a stainless steel substrate or anodized aluminum substrate on which aluminum (Al) or silver (Ag) film is deposited via a base layer by vacuum evaporation, vacuum sputtering or the like (refer to Japanese Patent Laid-open No. 2001-523835, Japanese Patent Laid-open No. 2002-530803) has been used.
Meanwhile, because it is possible to save energy of the above-described light reflecting device by effective utilization of light, wider promotion of the device is desired.
However, the light reflecting plate described in the aforementioned publicly known documents has the following problems.
First, the glass substrate has problems of workability and strength.
Then, the present inventor examined using a metal plate having high strength as a substrate.
The present inventor first considered evaporating silver being a reflective layer on galvanized steel sheet by an evaporation method. However, when silver is heated for evaporation purpose, the heating temperature influences a substrate side being a body to be deposited and zinc or the like on the substrate side melts first because zinc coating on the steel sheet has lower melting temperature than silver. For this reason, there is a problem that large unevenness occurs on substrate surface or the surface degenerates. Note that the problem becomes larger when substrate heating is required in performing evaporation.
Then, by using a plating method instead of evaporation, silver film was formed on galvanized or zinc alloy plated steel sheet. However, adhesion between the silver film and the galvanized or zinc alloy plated steel sheet was poor, and peel of silver film occurred.